The demand for clean and safe transportation fuel is increasing worldwide. This increased demand is, in part, a result of government regulations in various countries which attempt to reduce and/or eliminate certain chemicals that are typically contained in the transportation fuel. These government regulations can impose challenges on fuel refiners and producers to provide transportation fuel which contains lower amounts of the specified chemicals in order to comply with the various governmental regulations.
In the United States, a recent example of this is the Mobile Source Air Toxics 2 (MSAT2) benzene control program. Benzene is a byproduct of one or more chemical reactions in the reforming process associated with the refining of light petroleum distillate. Beginning in 2011, the MSAT2 regulations limit the level of benzene, a known carcinogen, in gasoline sold in the United States to an average of 0.62% of the total liquid volume of the gasoline.
It is believed that a typical reforming process might result in a reformate that has approximately 10% or less by weight of benzene. Generally, in a reforming process light petroleum distillate is contacted with catalyst in the presence of hydrogen at high temperatures to produce a high-octane liquid effluent that is rich aromatic compounds. Typically, there are a series of reactors in which the feedstock passes. After a reactor effluent from the last reactor is cooled, it is typically sent to a separator where a part of overhead vapor can be compressed and recycled to the reactor. The remaining reactor effluent can be sent to a product recovery section which includes passing the reactor effluent through various processing units and separating units some of which are designed to remove the benzene from the reactor effluent.
While current processes may be successful at obtaining appropriate benzene levels in separation steps of the entire process, the current methods require large amounts of heat and energy input. Additionally such methods typically also require large equipment sizes.
Additionally, competition in the gasoline refining industry constantly demands development of more energy efficient processing technology and methods—especially technology and methods that can competitively meet the current requirements.
Finally, beyond the current standards, future government regulations may further limit the amount of benzene in gasoline to an even lower level—creating a greater challenge for refiners and producers.
Therefore, it would be desirable to have a process that can effectively and efficiently separate benzene from a reactor effluent.